The conventionally-known vehicle body floor structures have a function for dealing with a side collision impact and are provided with a floor cross member disposed under front seats and extending in a left-right or width direction of the vehicle body, as disclosed for example in Japanese Patent Application Laid-Open Publication No. 2005-119492.
FIGS. 16A and 16B are views explanatory of the conventional vehicle body floor structure disclosed in the 2005-119492 publication. The disclosed vehicle body floor structure 201 includes: left and right side sills provided on left and right sides of a vehicle body floor; a floor cross member 203 disposed under front seats and extending in a left-right or width direction of the vehicle body, floor frames 204 extending substantially parallel to the side sills 202 and fixedly joined at its ends to the side sills 202. With such arrangements, the disclosed vehicle body floor structure 201 can efficiently disperse a side collision impact.
However, the side collision impact dispersion capability of the disclosed vehicle body floor structure 201 is not sufficient, and thus, the disclosed vehicle body floor structure has a room for further improvement. Besides, with the disclosed vehicle body floor structure 201, the floor frames 204 would become a resistance to an airstream caused during travel of the vehicle (i.e., traveling air) and flowing under the floor panel 205, and thus, it is difficult to achieve an enhanced aerodynamic performance.
Further, Japanese Patent Publication No. 3434199, for example, discloses a vehicle body floor structure which includes a floor panel and left and right front floor frames fixedly joined to the floor panel and extending in a front-rear (i.e., longitudinal or length) direction of the vehicle and has a function for securing an suitable in-vehicle space against a frontal collision of the vehicle.
FIG. 17 is a view explanatory of the vehicle body floor structure disclosed in the 3434199 publication. In the disclosed vehicle body floor structure 221, the floor frames 224 are disposed under the floor panel, a floor cross member 225 extends in the width direction of the vehicle over the floor panel 223, and left and right forwardly-extending reinforcing members 226 and reinforcing gussets 227 are joined to the floor cross member 225. Such arrangements can increase the strength of the floor.
However, if the in-vehicle space is to be increased, the vehicle body floor structure disclosed in the No. 3434199 publication would present the problem that the height of the floor frame 224 and hence the ground height of the vehicle (from the ground surface) has to be lowered. Further, because the left and right forwardly-extending reinforcing members 226 and reinforcing gussets 227 are provided on the left and right sides of the vehicle floor, the weight of the disclosed vehicle body floor structure would undesirably increase to a considerable degree. Furthermore, because an airstream flowing under the floor panel 223 during travel of the vehicle (traveling air) interferes with the floor frames 224, it is difficult to achieve an enhanced aerodynamic performance.